1. Field of the Invention
The present invention relates to an improvement in an engine including a cylinder head having a valve-operating chamber with an open upper surface. The cylinder head is coupled to a cylinder block by a plurality of fastening bolts. A head cover is coupled to the cylinder head to close the valve-operating chamber.
2. Description of the Related Art
Such a conventional engine is disclosed, for example, in Japanese Utility Model Publication No. 2-32849.
In the conventional engine, in coupling a cylinder head to a cylinder block by a plurality of fastening bolts, one or more of the fastening bolts is, or are, disposed in a valve-operating chamber in the cylinder head. A bottom wall of the valve-operating chamber is fastened to the cylinder head. In such an arrangement, the bottom wall of the valve-operating chamber is brought into close contact with the cylinder block to affect the cooling of portions around the bottom wall of the valve-operating chamber, as well as portions around the combustion chamber.